As expected, this file shows that Yahoo uses JSON to return suggestions to the browser. If we break down the URL, we can understand what the parameters mean:

output=fxjsonp – the output format

nresults=10 – the number of results returned

command=google – the query used for suggestions

With URLs like this, you can often change the output parameter to return a different output format. By trying a few simple alternatives, we are able to view 30 suggestions (which appears to be the default maximum) in the following common formats:

What’s more interesting is that changing the output parameter to text gives you full access to a crude interface for something called “Query Inspector” which allows you to try some of the more advanced features of Yahoo Search Suggest.

A screenshot of the basic Query Inspector interface and a cache just in case the page disappears.

After playing with the results, I’m assuming some of the more advanced parameters can be used as follows:

regexp – a regular expression used to exclude results (for example, ^google will exclude all suggestions starting with the word “google”)

maxnresults – the maximum number of results

nocache – presumably forces the database to be queried instead of using a cached copy, which I guess would be useful if you were changing the algorithms

droprotated – setting this to 1 seems to make sure your suggestions usually start with your query

stars – when set to 1 the results will include some kind of 5-based star rating

data – selecting any one of these options (0 = none; 1 = key; 3 = score; 7 = all) displays values that are perhaps based on the number of queries performed for each suggestion in a given period – e.g. [tony ruscoe] = 48, [philipp lenssen] = 689, [google] = 472642086

Yah00Magik – this is always set to “chickenLittle” which is obviously Yahoo’s magic word... ;-)

Ever wanted to know what Yahoo would suggest as the top 1000 phrases containing the word “google"? Here’s your answer!

The six links provided beneath the form fields – Home, Queries, 5 Min Stats, Hourly Stats, Daily Stats and Help – all currently lead to Yahoo’s 404 page, but these were presumably there to view live traffic and statistics during development.

It’s unusual for a company to expose an interface like this. Competitors could potentially use it to gain an insight into how the suggestion algorithms work and developers could screenscrape the data to use it in their own applications. If Yahoo doesn’t mind people doing that, perhaps they’ll release this in future as one of their many web services.

Update: Yahoo have now removed the Query Inspector interface. Applying the output=text parameter now returns the same as output=fxjsonp. They’ve also restricted the number of suggestions returned to 10 and disabled some of the advanced parameters.